1. Field of the Invention
The present invention relates to a method of processing a substrate, and a method of and program for manufacturing an electronic device, and more particularly to a method of manufacturing an electronic device having a low dielectric constant insulating film formed on a surface thereof.
2. Description of the Related Art
In a method of manufacturing an electronic device in which an electronic device is manufactured from a silicon wafer (hereinafter referred to merely as a “wafer”), a film formation step of forming a conductive film or an insulating film on a surface of the wafer by CVD (chemical vapor deposition) or the like, a lithography step of forming a photoresist layer in a desired pattern on the formed conductive film or insulating film, and an etching step of fabricating the conductive film into gate electrodes, or fabricating wiring grooves or contact holes in the insulating film, with plasma using the photoresist layer as a mask are repeatedly implemented in this order.
An electronic device manufactured using such a method of manufacturing an electronic device thus has a structure in which insulating films are disposed between conductive films that form electrodes or wiring. Such an insulating film is generally referred to as an “interlayer insulating film”.
In recent years, there have been demands to realize a higher degree of integration for electronic devices, and to achieve this, the dimension to which wiring grooves are required to be fabricated has become smaller, and the required spacing between adjacent pieces of wiring has also become narrower. As the wiring groove fabrication dimension becomes smaller and the wiring spacing becomes narrower, the parasitic resistance R and the parasitic capacitance C of the wiring increases, and hence wiring delay (RC delay) caused thereby arises, and thus the speed of transmission of signals along the wiring decreases. Such wiring delay increases as the parasitic resistance R and the parasitic capacitance C increase, and hence to resolve the problem of wiring delay, the parasitic resistance R and the parasitic capacitance C must be reduced.
As a technique for reducing the parasitic capacitance C, reducing the relative dielectric constant of an interlayer insulating film is effective, and hence various low-relative dielectric constant (low-K) interlayer insulating films have been developed.
In general, SiO2 is used as a material of interlayer insulating films. As a method of reducing the relative dielectric constant of SiO2, a method in which the SiO2 is doped with fluorine is known, but the doped fluorine tends to be released from the SiO2, and hence SiOC type low dielectric constant interlayer insulating film materials, organic polymer type coated low dielectric constant interlayer insulating film materials, for example “SiLK” (registered trademark, The Dow Chemical Company), and so on that are doped with carbon instead of fluorine are currently being developed. Here, a relative dielectric constant of not more than 3.0 is referred to as a “low dielectric constant”. Materials representative of those used in low dielectric constant interlayer insulating films are shown in Table 1 below.
TABLE 1Relative dielectricTypeMaterialconstantInorganicSiO2  4SiOF3.4 to 3.6Si—H-containing SiO2 (HSQ)2.8 to 3.0Porous silica film<3.0Organic filmCarbon-containing SiO2 (SiOC)2.7 to 2.9Methyl group-containing SiO2 (MSQ)2.7 to 2.9Porous MSQ2.4 to 2.7Polymeric filmsPolyimide film3.0 to 3.5PARERIN film2.7 to 3.0PTFE Film2.0 to 2.4Amorphous carbon (F added)<2.5
However, for an SiOC type low dielectric constant interlayer insulating film or organic polymer type coated low dielectric constant interlayer insulating film, a surface damaged layer having a reduced carbon concentration is formed on a disposed surface of the interlayer insulating film upon carrying out plasma processing in, for example, a reactive ion etching step of fabricating a wiring groove or the like in the interlayer insulating film, or an ashing step of removing a photoresist layer formed on the interlayer insulating film (see, for example, D. Shamiryan, “Comparative study of SiOCH low-k films with varied porosity interacting with etching and cleaning plasma”, J. Vac. Sci. Technol. B20(5), American Vacuum Society, September 2002, p. 1928). Such a surface damaged layer has similar properties to SiO2 (the native oxide), being readily dissolved in a subsequently implemented wet etching step using a liquid chemical (HF, NH4F, etc.), and moreover undergoing volume shrinkage in a heat treatment step. It is thus necessary to implement the etching step or ashing step such that a surface damaged layer is not formed, or else remove a formed surface damaged layer before the surface damaged layer is covered with a conductive film or the like.
As an ashing process in which a surface damaged layer is not formed, a process using an H2O (water) plasma instead of an O2 (oxygen) plasma is known (see, for example, Yoda, “Ko-seino haisen gijutsu” (“High-performance wiring techniques”, Toshiba Review, Vol. 59, No. 8, 2004, p. 18), and as a method of removing a surface damaged layer, a method of removal through liquid chemical treatment using an organic solvent and NH4F (see, for example, Japanese Laid-open Patent Publication (Kokai) No. 2002-303993) is known.
However, in the process using plasma, a high energy is applied by the plasma to the electronic devices, which have a high degree of integration and hence have fine wiring, and hence the fine wiring may be damaged.
It is thus preferable to use the method of removing the surface damaged layer through liquid chemical treatment that does not use plasma. However, with such liquid chemical treatment, the surface damaged layer continues to be removed while in contact with the liquid chemical, and hence it is difficult to control the amount removed of the surface damaged layer, and furthermore after removal of the surface damaged layer, the surface of the low dielectric constant interlayer insulating film becomes hydrophilic due to OH groups (hydroxyl groups) formed thereon through water in the liquid chemical, and as a result there is a problem that the wiring reliability decreases through moisture absorption.